Dual pump regulator system for a motor vehicle transmission

ABSTRACT

An apparatus and method are disclosed for controlling fluid flow in a motor vehicle transmission. At least one friction engagement device is fluidly coupled to a first pump, and a lubrication and cooling sub-system is normally fluidly coupled to a second pump. Illustratively, when a flow rate of the fluid in the first fluid passageway is less than a threshold fluid flow rate, a temperature of the fluid is greater than a temperature threshold and a fluid flow demand is greater than a fluid flow demand threshold, fluid flow from the second pump to the lubrication and cooling sub-system is blocked and fluid supplied by the second pump is instead directed to the at least one friction engagement device such that fluid is supplied by both the first and second pumps only to the at least one friction engagement device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 13/325,412 entitled “DUAL PUMP REGULATOR SYSTEM FOR A MOTOR VEHICLETRANSMISSION,” which was filed on Dec. 14, 2011, and which claimspriority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser.No. 61/423,296, filed Dec. 15, 2010, the entirety of each of which isherein incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to motor vehicle transmissions,and more specifically to systems and methods for controlling thepressure and flow of fluids in such transmissions.

BACKGROUND

Conventional transmission fluid supply systems in motor vehicletransmission may include one or more fluid pumps that supply thetransmission fluid to various components and sub-systems of thetransmission. In transmissions which include two or more such fluidpumps, it is desirable to control the pressure and/or flow of fluidssupplied by such pumps to satisfy fluid flow demands during variousfluid pressure, temperature and/or flow conditions.

SUMMARY

The present application discloses one or more of the features recited inthe appended claims and/or the following features which alone or in anycombination, may comprise patentable subject matter.

The present invention may comprise one or more of the features recitedin the attached claims, and/or one or more of the following features andcombinations thereof. An apparatus for controlling fluid flow in a motorvehicle transmission may comprise a first pump driven by an input shaftof the transmission to supply fluid from a source of fluid to at leastone friction engagement device via a first fluid passageway, a secondpump driven by the input shaft of the transmission to normally supplyfluid from the source of fluid to a lubrication and cooling sub-systemof the transmission via a second fluid passageway, a first valve fluidlycoupled between the first and second fluid passageways and directingfluid from the second fluid passageway to the first fluid passagewaywhen fluid pressure in the second fluid passageway is greater than fluidpressure in the first fluid passageway by at least a threshold pressureamount, and a second valve fluidly coupled to the first and second fluidpassageways and to the lubrication and cooling sub-system. The secondvalve may block the first and second fluid passageways from thelubrication and cooling sub-system when a flow rate of the fluid in thefirst fluid passageway is less than a first threshold fluid flow rate, atemperature of the fluid is greater than a temperature threshold and afluid flow demand is greater than a fluid flow demand threshold suchthat fluid pressure in the second fluid passageway exceeds the fluidpressure in the first fluid passageway by at least the thresholdpressure amount. Fluid may thus be supplied by the first and secondpumps only to the at least one friction engagement device via the firstfluid passageway.

The first valve may comprise a ball check valve configured to allowfluid flow from the second fluid passageway to the first fluidpassageway when the fluid pressure in the second fluid passageway isgreater than the fluid pressure in the first fluid passageway by atleast the threshold pressure amount and to otherwise block fluid flowbetween the first and second fluid passageways.

The second valve may comprise a spool having one end in fluidcommunication with the first fluid passageway and an opposite endpositioned in a spring pocket under bias of a spring in the direction ofthe one end, the spring pocket receiving fluid at a controlled pressure.A position of the spool within the second valve may be a function of thefluid pressure in the first passageway, the controlled pressure of thefluid in the spring pocket and a biasing force of the spring. Theapparatus may further comprise a trim valve having a fluid inlet fluidlycoupled to the first fluid passageway and a fluid outlet fluidly coupledto the spring pocket of the second valve. The trim valve may beresponsive to a control signal to supply fluid at the controlledpressure to the spring pocket of the second valve. The apparatus mayfurther comprise a control circuit including a memory havinginstructions stored therein executable by the control circuit to producethe control signal. The apparatus may further comprise means fordetermining a rotational speed of the input shaft of the transmission.The memory may have an emergency low speed threshold stored therein thatis correlated with the first threshold fluid flow rate, and theinstructions stored in the memory may include instructions executable bythe control circuit to determine whether the flow rate of the fluid inthe first fluid passageway is less than a first threshold fluid flowrate by determining whether the rotational speed of the input shaft ofthe transmission is less than the emergency low speed threshold. Theapparatus may further comprise means for determining a temperature ofthe fluid supplied by the first and second pumps and producing acorresponding temperature value. The temperature threshold and the fluidflow demand threshold may be stored in the memory, and the instructionsstored in the memory may include instructions executable by the controlcircuit to determine the fluid flow demand and to produce the controlsignal if the rotational speed of the input shaft of the transmission isless than the emergency low speed threshold, the temperature value isgreater than the threshold temperature and the fluid flow demand isgreater than the fluid flow demand threshold.

The instructions stored in the memory may include instructionsexecutable by the control circuit to modulate the control signal as afunction of the fluid pressure in the first passageway and the biasingforce of the spring such that the fluid pressure supplied by the trimvalve to the spring pocket controls the spool to a position in which thesecond valve blocks the first and second fluid passageways from thelubrication and cooling sub-system such that fluid is supplied by thefirst and second pumps only to the at least one friction engagementdevice via the first fluid passageway.

The second valve may block the first fluid passageway from thelubrication and cooling sub-system and fluidly couple the second fluidpassageway to the lubrication and cooling sub-system when the flow rateof the fluid in the first fluid passageway is greater than the firstthreshold fluid flow rate but less than a second threshold fluid flowrate and the temperature of the fluid is less than the temperaturethreshold such that the fluid pressure in the second fluid passageway isless than the fluid pressure in the first fluid passageway by at leastthe threshold pressure amount. Fluid may thus be supplied by the firstpump only to the at least one friction engagement device via the firstfluid passageway and fluid may also be supplied by the second pump onlyto the lubrication and cooling sub-system via the second fluidpassageway. The second valve may couple the first and second fluidpassageways to the lubrication and cooling sub-system when the flow rateof the fluid in the first fluid passageway is greater than the secondthreshold fluid flow rate and the temperature of the fluid is greaterthan the temperature threshold such that the fluid pressure in thesecond fluid passageway is less than the fluid pressure in the firstfluid passageway by at least the threshold pressure amount. Fluid maythus be supplied by the first pump to the at least one frictionengagement device and to the lubrication and cooling system via thefirst fluid passageway and fluid may also be supplied by the second pumpto the lubrication and cooling sub-system via the second fluidpassageway. The second valve may comprise a spool having one end influid communication with the first fluid passageway and an opposite endpositioned in a spring pocket under bias of a spring in the direction ofthe one end. A position of the spool within the second valve may be afunction of the fluid pressure in the first passageway, fluid pressurein the spring pocket and a biasing force of the spring, and the secondvalve may regulate fluid pressure within the first fluid passageway to afixed fluid pressure as a function of the biasing force of the springand of an area of the one end of the spool when the spring pocket isexhausted. The apparatus may further comprise means for selectivelyexhausting the spring pocket of the second valve.

The transmission may further comprise another fluid-using sub-system inaddition to the at least one friction engagement device and thelubrication and cooling subsystem. The another fluid-using subsystemfluidly may be coupled to the second valve via a third fluid passageway.The second valve may further block the first and second fluidpassageways from the third fluid passageway when the flow rate of thefluid in the first fluid passageway is less than the first thresholdfluid flow rate, the temperature of the fluid is greater than thetemperature threshold and the fluid flow demand is greater than thefluid flow demand threshold. Fluid may flow to the another fluid-usingsub-system via either of the first and second fluid pumps may thus beblocked. The second valve may block the first fluid passageway from thelubrication and cooling sub-system, fluidly couple the first fluidpassageway to the third fluid passageway and block the second fluidpassageway from the lubrication and cooling sub-system when the flowrate of the fluid in the first fluid passageway is greater than thefirst threshold fluid flow rate but less than a second threshold fluidflow rate, the temperature of the fluid is greater than the temperaturethreshold and the fluid flow demand is greater than the fluid flowdemand threshold such that the fluid pressure in the second fluidpassageway is less than the fluid pressure in the first fluid passagewayby at least the threshold pressure amount. Fluid may thus be supplied bythe first and second pumps only to the at least one friction engagementdevice and the another fluid-using sub-system via the first fluidpassageway. The second valve may block the first fluid passageway fromthe lubrication and cooling sub-system, fluidly couple the first fluidpassageway to the third fluid passageway and fluidly couple the secondfluid passageway to the lubrication and cooling sub-system when the flowrate of the fluid in the first fluid passageway is greater than thesecond threshold fluid flow rate but less than a third threshold fluidflow rate and the temperature of the fluid is less than the temperaturethreshold such that the fluid pressure in the second fluid passageway isless than the fluid pressure in the first fluid passageway by at leastthe threshold pressure amount. Fluid may thus be supplied by the firstpump only to the at least one friction engagement device and the anotherfluid-using sub-system via the first fluid passageway and fluid may besupplied by the second pump only to the lubrication and coolingsub-system via the second fluid passageway. The second valve may fluidlycouple the first and second fluid passageways to the lubrication andcooling sub-system and fluidly couple the first fluid passageway to thethird fluid passageway when the flow rate of the fluid in the firstfluid passageway is greater than the third threshold fluid flow rate andthe temperature of the fluid is greater than the temperature thresholdsuch that the fluid pressure in the second fluid passageway is less thanthe fluid pressure in the first fluid passageway by at least thethreshold pressure amount. Fluid may thus be supplied by the first pumpto the at least one friction engagement device, the another fluid-usingsub-system and the lubrication and cooling system via the first fluidpassageway and fluid may be supplied by the second pump to thelubrication and cooling sub-system via the second fluid passageway.

The second valve may comprise a spool having one end in fluidcommunication with the first fluid passageway and an opposite endpositioned in a spring pocket under bias of a spring in the direction ofthe one end. A position of the spool within the second valve may be afunction of the fluid pressure in the first passageway, fluid pressurein the spring pocket and a biasing force of the spring, and the secondvalve may regulate fluid pressure within the first fluid passageway to afixed fluid pressure as a function of the biasing force of the springand of an area of the one end of the spool when the spring pocket isexhausted. The apparatus may further comprise means for selectivelyexhausting the spring pocket of the second valve. The anotherfluid-using sub-system may comprise one of a variator and a torqueconverter.

An apparatus for controlling fluid flow in a motor vehicle transmissionincluding at least one friction engagement device and a fluid-usingsub-system separate from and addition to the at least one frictionengagement device may comprise a first pump driven by an input shaft ofthe transmission to supply fluid from a source of fluid to the at leastone friction engagement device via a first fluid passageway and tonormally supply fluid from the source of fluid to the fluid-usingsub-system via the first fluid passageway, a second pump driven by theinput shaft of the transmission to normally supply fluid from the sourceof fluid to a lubrication and cooling sub-system of the transmission viaa second fluid passageway, a first valve fluidly coupled between thefirst and second fluid passageways and directing fluid from the secondfluid passageway to the first fluid passageway when fluid pressure inthe second fluid passageway is greater than fluid pressure in the firstfluid passageway by at least a threshold pressure amount, and a secondvalve fluidly coupled to the first and second fluid passageways, to thefluid-using sub-system and to the lubrication and cooling sub-system.The second valve may block the first and second fluid passageways fromthe lubrication and cooling sub-system and fluidly coupling the firstfluid passageway to the fluid-using sub-system when a flow rate of thefluid in the first fluid passageway is less than a first threshold fluidflow rate, a temperature of the fluid is greater than a temperaturethreshold and a fluid flow demand is greater than a fluid flow demandthreshold such that fluid pressure in the second fluid passagewayexceeds the fluid pressure in the first fluid passageway by at least thethreshold pressure amount. Fluid may thus be supplied by the first andsecond pumps only to the at least one friction engagement device and tothe fluid-using sub-system via the first fluid passageway. The anotherfluid-using sub-system may comprise one of a variator and a torqueconverter.

An apparatus for controlling fluid flow in a motor vehicle transmissionincluding at least one friction engagement device, a fluid-usingsub-system separate from and addition to the at least one frictionengagement device and a lubrication and cooling sub-system may comprisea first pump driven by an input shaft of the transmission to supplyfluid from a source of fluid to the at least one friction engagementdevice via a first fluid passageway, a second pump driven by the inputshaft of the transmission to supply fluid from the source of fluid to asecond fluid passageway, and a valve fluidly coupled to the first andsecond fluid passageways, to the fluid-using sub-system and to thelubrication and cooling sub-system. The valve may fluidly couple thefirst fluid passageway to the fluid-using sub-system and fluidly couplethe second fluid passageway to the lubrication and cooling sub-systemwhen a flow rate of the fluid in the first fluid passageway is greaterthan a threshold fluid flow rate and a temperature of the fluid is lessthan a temperature threshold. Fluid may thus be supplied only by thefirst pump to the at least one friction engagement device and to thefluid-using sub-system via the first fluid passageway and fluid may besupplied only by the second fluid pump to the lubrication and coolingsub-system via the second fluid passageway. The another fluid-usingsub-system may comprise one of a variator and a torque converter.

An apparatus for controlling fluid flow in a motor vehicle transmissionincluding at least one friction engagement device and a lubrication andcooling sub-system may comprise a first pump driven by an input shaft ofthe transmission to supply fluid from a source of fluid to the at leastone friction engagement device via a first fluid passageway, a secondpump driven by the input shaft of the transmission to supply fluid fromthe source of fluid to a second fluid passageway, and a valve fluidlycoupled to the first and second fluid passageways and to the lubricationand cooling sub-system. The valve may fluidly couple the first fluidpassageway to the lubrication and cooling sub-system when a flow rate ofthe fluid in the first fluid passageway is greater than a thresholdfluid flow rate and a temperature of the fluid is greater than atemperature threshold. Fluid may thus be supplied by the first pump tothe at least one friction engagement device and to the lubrication andcooling sub-system via the first fluid passageway and fluid may besupplied by the second fluid pump to the lubrication and coolingsub-system via the second fluid passageway. The another fluid-usingsub-system may comprise one of a variator and a torque converter.

An apparatus for controlling fluid flow in a motor vehicle transmissionincluding at least one friction engagement device may comprise a firstpump driven by an input shaft of the transmission to supply fluid from asource of fluid to the at least one friction engagement device via afirst fluid passageway, a valve including a spool having one end influid communication with the first fluid passageway and an opposite endpositioned in a spring pocket under bias of a spring in the direction ofthe one end, and means for selectively supplying a modulated pressure toor exhausting the spring pocket of the valve. A position of the spoolwithin the valve may be a function of the fluid pressure in the firstpassageway, fluid pressure in the spring pocket and a biasing force ofthe spring. The valve may regulate fluid pressure within the first fluidpassageway as a function of the biasing force of the spring, the fluidpressure within the first fluid passageway and the modulated pressurewhen the modulated pressure is supplied to the spring pocket of thevalve. The valve may also regulate fluid pressure within the first fluidpassageway to a fixed fluid pressure as a function of the biasing forceof the spring and of an area of the one end of the spool when the springpocket is exhausted.

Additional features and advantages of the invention will become apparentto those skilled in the art upon consideration of the following detaileddescription of illustrated embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

DESCRIPTION OF THE DRAWINGS

The systems and methods described herein are illustrated by way ofexample and not by way of limitation in the accompanying figures. Forsimplicity and clarity of illustration, elements illustrated in theFIGS. are not necessarily drawn to scale. For example, the dimensions ofsome elements may be exaggerated relative to other elements for clarity.Further, where considered appropriate, reference labels have beenrepeated among the FIGS. to indicate corresponding or analogouselements.

FIG. 1 is a block diagram of one illustrative embodiment of a system forcontrolling operation of a toroidal traction drive motor vehicletransmission.

FIG. 2A is a diagram illustrating operation of one illustrativeembodiment of a variator that forms part of the toroidal traction drivemotor vehicle transmission illustrated in FIG. 1.

FIG. 2B is a diagram further illustrating operation of the variator ofFIG. 2A.

FIG. 3 is a schematic diagram of one illustrative embodiment of theelectro-hydraulic control system that forms part of the toroidaltraction drive motor vehicle transmission illustrated in FIG. 1.

FIG. 4 is a magnified view of the clutch and variator fluid pressure andfluid flow control sub-system of the electro-hydraulic control systemillustrated in FIG. 3 showing one operating state of the dual pumppressure and flow regulator valve.

FIG. 5 is a view similar to that of FIG. 4 showing another operatingstate of the dual pump pressure and flow regulator valve.

FIG. 6 is another view similar to that of FIG. 4 showing yet anotheroperating state of the dual pump pressure and flow regulator valve.

FIG. 7 is yet another view similar to that of FIG. 4 showing stillanother operating state of the dual pump pressure and flow regulatorvalve.

FIG. 8 is still another view similar to that of FIG. 4 showing a furtheroperating state of the dual pump pressure and flow regulator valve.

FIG. 9 is another view similar to that of FIG. 4 showing the clutch andvariator fluid pressure and fluid flow control sub-system of FIGS. 4-8implemented in an automatic transmission in which a conventional torqueconverter replaces the variator illustrated in FIGS. 1-3.

FIG. 10 is yet another view similar to that of FIG. 4 showing the clutchand variator fluid pressure and fluid flow control sub-system of FIGS.4-8 implemented in a conventional automatic transmission in which thevariator illustrated in FIGS. 1-3 is omitted.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to a number of illustrativeembodiments shown in the attached drawings and specific language will beused to describe the same.

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Referring now to FIG. 1, a block diagram is shown of one illustrativeembodiment of a system 10 for controlling operation of a toroidaltraction drive automatic transmission 14. In the illustrated embodiment,a power plant or energy center 12 is coupled to an automatictransmission 14 such that a rotatable output shaft 16 of the power plant12 is coupled to a rotatable input shaft 18 of the transmission 14 in aconventional manner. The input shaft 18 is coupled, in the illustratedembodiment, to a combination variator and gear set 20 that furtherincludes a plurality of selectively engageable friction devices, e.g.,one or more conventional, selectively engageable clutches or the like,and an output of the combination variator and gear set 20 is coupled toa rotatable output shaft 22. The combination variator and gear set 20 isillustratively controlled by an electro-hydraulic control system 24,some of the details of which will be described in greater detailhereinafter.

The power plant 12 is generally an apparatus that produces rotationaldrive power at the output shaft 16. Examples of the power plant 12include, but should not be limited to, one or any combination of a oneor more engines, such as an internal combustion engine of the sparkignited, compression ignition or other variety, a steam engine, or typeof engine that produces mechanical energy from one or more other fuelsources, one or more electrical generators, and the like.

The combination variator and gear set 20 illustratively includes aconventional full-toroidal, traction-drive variator that is coupled to aconventional gear set. Referring to FIGS. 2A and 2B, one illustrativeembodiment of some of the structural features of such a full-toroidal,traction-drive variator 40 is shown. In the illustrated embodiment, thevariator 40 includes a pair of opposing, toroidal-shaped disks 42 and 44that rotate independently of each other. For example, the disk 42 isillustratively directly connected to the input shaft 18 of thetransmission 14 such that the disk 42 is directly rotatably driven bythe power plant 12. Alternatively, the disk 42 may be connected to theinput shaft 18 of the transmission through one or more structures, e.g.,one or more gear sets or other structures. For purposes of thisdisclosure, the term “coupled” used to described the relationshipbetween the disk 42 and the input shaft 18 of the transmission isdefined as either a direct connection, i.e., engagement, between thedisk 42 and the input shaft 18 of the transmission 14 or an indirectconnection between the disk 42 and the input shaft 18 of thetransmission 14 through one or more structures interposed between thedisk 42 and the input shaft 18 of the transmission 14. Illustratively,the disk 44 is rigidly coupled to an output shaft 46 of the variator 40,and is rotatably coupled to the shaft 18 such that the disk 44 rotatesfreely about the shaft 18. The output shaft 46 of the variator 40 iscoupled directly, or indirectly through one or more transmission gears,to the output shaft 22 of the transmission 14 such that output shaft 46of the variator 40 drives one or more wheels of a vehicle (not shown)carrying the power plant 12 and transmission 14.

A number of rollers 48 are illustratively positioned between opposinginner, arcuate-shaped surfaces, e.g., concave surfaces, of the disks 42and 44, and a traction fluid (not shown) is disposed between the rollingsurface of each such roller 48 and the inner surfaces of the disks 42and 44. In the illustrated embodiment, the rolling surfaces of thevarious rollers 48 therefore do not contact, in a structural sense, theinner surface of either disk 42, 44; rather torque is transmitted by thevarious rollers 48 between the two disks 42, 44 via the traction fluid.It is because torque is transferred between the two disks 42, 44 via thetraction fluid and not via structural contact between the rollingsurfaces of the rollers 48 and the arcuate inner surfaces of the disks42, 44 that the variator is referred to as a traction-drive apparatus.

In the embodiment illustrated in FIGS. 2A and 2B, two such rollers 48 ₁and 48 ₂ are shown operatively positioned between the opposing innersurfaces of the two disks 42, 44. A roller actuator 50 ₁, e.g., in theform of a conventional hydraulically actuated piston, is coupled to theroller 48 ₁ via a bracket 52 ₁, and another roller actuator 50 ₂, e.g.,in the form of another conventional hydraulically actuated piston, iscoupled to the roller 48 ₂ via a bracket 52 ₂. It will be understoodthat the brackets 52 ₁ and 52 ₂ do not represent rotatable shafts aboutwhich the rollers 48 ₁ and 48 ₂ may be rotatably driven. Rather, thebrackets 52 ₁ and 52 ₂ represent structures about which the rollers 48 ₁and 48 ₂ rotate. In one actual implementation, for example, the brackets52 ₁ and 52 ₂ are configured to attach to the central hub of the rollers48 ₁ and 48 ₂ on either side thereof such that the brackets 52 ₁ and 52₂ and actuators 50 ₁ and 50 ₂ would extend generally perpendicular tothe page illustrating FIGS. 2A and 2B.

The hydraulically controlled actuators 50 ₁ and 50 ₂ are eachillustratively controllable by selectively controlling a high-sidehydraulic pressure applied to one side of the actuators 50 ₁ and 50 ₂and a low-side hydraulic pressure applied to the opposite side of theactuators 50 ₁ and 50 ₂. Traction force generated by the net hydraulicpressure, i.e., the difference between the applied high and low sidehydraulic pressures, is transmitted by the rollers 48 ₁ and 48 ₂ to thetwo disks 42, 44 via the traction fluid, and this applied traction forcedefines the torque transmitted between the two disks 42, 44. Thus, adirect relationship exists between the net hydraulic pressure applied tothe actuators 50 ₁ and 50 ₂ and the magnitude of the torque transmittedbetween the two disks 42, 44. Each roller 48 ₁ and 48 ₂ moves andprecesses to the location and tilt angle relative to the disks 42, 44required to transmit the torque to the disks 42, 44 defined by the nethydraulic pressure applied to the hydraulic actuators 50 ₁ and 50 ₂. Adifference in the magnitude of the net hydraulic pressure applied to theactuators 50 ₁ and 50 ₂ changes the torque transmitted to the outputshaft 46. The direction of the torque applied by the rollers 48 ₁ and 48₂ to the two disks 42, 44, is determined by the relative magnitudes ofthe high and low side pressures applied to the actuators 50 ₁ and 50 ₂.In one illustrative embodiment, for example, the rollers 48 ₁ and 48 ₂apply a positive torque to the two disks 42, 44 if the high sidehydraulic pressure is greater than the low side hydraulic pressure, andthe rollers 48 ₁ and 48 ₂ conversely apply a negative torque to the twodisks if the low side pressure is greater than the high side hydraulicpressure. In alternative embodiments, the rollers 48 ₁ and 48 ₂ mayapply a positive torque to the two disks 42, 44 if the low sidehydraulic pressure is greater than the high side hydraulic pressure, andthe rollers 48 ₁ and 48 ₂ may conversely apply a negative torque to thetwo disks if the high side pressure is greater than the low sidehydraulic pressure. In any case, the rollers 48 ₁ and 48 ₂ arefree-castoring, and are responsive to the actuators 50 ₁ and 50 ₂ toseek a position that provides the correct ratio match of engine anddrive train speeds based on input energy equaling output energy.

In one illustrative implementation, the variator 40 includes two sets orpairs of disks 42 and 44, with the pairs of the disks 42 rigidly coupledto each other and with the pairs of the disks 44 also rigidly coupled toeach other, such that the embodiment illustrated in FIGS. 2A and 2Brepresents one-half of such an implementation. In this illustrativeimplementation, three rollers are positioned between each opposing setof disks 42, 44 for a total of six rollers 48 ₁-48 ₆ and sixcorresponding hydraulically controlled actuators 50 ₁-50 ₆. It will beunderstood, however, that this particular implementation of the variator40 is shown and described only by way of example, and that otherembodiments of the variator 40 that include more or fewer pairs of disks42, 44, that include more or fewer rollers 48 and hydraulicallycontrolled actuators 50, and/or that are configured to be only partiallytoroidal in shape, may alternatively be used. It will further beunderstood that while the operation of the variator 40 is illustratedand described herein as being generally hydraulically controlled, thisdisclosure contemplates embodiments in which operation of the variator40 is controlled via purely electronic or electro-mechanical structures.

Referring again to FIG. 1, the gear set within the combination variatorand gear set 20 illustratively includes one or more conventionalplanetary gear set(s) and/or other gear set(s) that define(s) at leasttwo automatically selectable gear ratios and that is coupled to, orintegrated with, the variator, e.g., the variator 40 illustrated anddescribed with respect to FIG. 2. The combination variator and gear set20 further illustratively includes a number of conventional frictiondevices, e.g., clutches, which may be selectively controlled to therebycontrol shifting of the transmission 14 between the two or more gearratios. In alternate embodiments, the gear set may include more than oneplanetary gear set, one or more planetary gear sets in combination withone or more other conventional gear sets, or exclusively one or morenon-planetary gear sets.

In the example embodiment illustrated in FIG. 1, the transmission 14includes three friction devices, e.g., in the form of three conventionalclutches C1, C2 and C3. In this embodiment, each clutch C1, C2 and C3 isoperated in a conventional manner, e.g., via fluid pressure, under thecontrol of the electro-hydraulic control system 24. In this regard, afluid path 25 ₁ is fluidly coupled between the electro-hydraulic controlsystem 24 and the clutch C1, a fluid path 25 ₂ is fluidly coupledbetween the electro-hydraulic control system 24 and the clutch C2, and afluid path 25 ₃ is fluidly coupled between the electro-hydraulic controlsystem 24 and the clutch C3. The electro-hydraulic control system 24 isoperable to control operation of the clutches C1-C3 by controlling fluidpressure within the fluid paths 25 ₁-25 ₃ respectively.

The gear set and the clutches C1, C2 and C3 are illustratively arrangedto provide four separate modes of operation of the transmission 14, andthe various operating modes of the transmission 14 are selectivelycontrolled by the operation of the clutches C1, C2 and C3. In a firstoperating mode, M1, for example, the clutch C1 is applied, e.g.,engaged, while the clutches C2 and C3 are released, e.g., disengaged,and in this mode forward or reverse launch can be accomplished, and thevehicle carrying the transmission 14 can be operated at vehicle speedsup to about 10 miles per hour. In a second operating mode, M2, asanother example, the clutch C2 is engaged while the clutches C1 and C3are disengaged, and in this mode the vehicle can be operated at vehiclespeeds in the range of about 10-30 miles per hour. In a third operatingmode, M3, as yet another example, the clutch C3 is engaged while theclutches C1 and C2 are disengaged, and in this mode the vehicle can beoperated at vehicle speeds greater than about 30 miles per hour. In afourth mode, M0, as a final example, the clutches C1, C2 and C3 are alldisengaged, and in this mode the transmission 14 is in neutral. Withineach operating mode, torque applied to the output shaft 22 of thetransmission 14 is controlled by the variator, e.g., the variator 40. Inthe transitional states between the various operating modes M1, M2 andM3, the variator torque is illustratively reversed to assist transitionsfrom one operating mode to the next.

The system 10 further includes a transmission control circuit 30 thatcontrols and manages the overall operation of the transmission 14. Thetransmission control circuit 30 includes a number, M, of operatingparameter inputs, OP₁-OP_(M), that are electrically connected tocorresponding operating parameter sensors included within theelectro-hydraulic control system 24 via corresponding signal paths 26₁-26 _(M), wherein M may be any positive integer. The one or moreoperating parameter sensors included within the electro-hydrauliccontrol system 24, examples of which will be described hereinafter,produce corresponding operating parameter signals on the signal paths 26₁-26 _(M), which are received by the transmission control circuit 30.The transmission 14 further illustratively includes a transmission inputshaft speed sensor 33 positioned to sense a rotational speed of thetransmission input shaft 18. The speed sensor 33 is electricallyconnected to a transmission input speed (TIS) input of the controlcircuit 30 via a signal path 34. The speed sensor 33 may be conventionaland is configured to produce a speed signal corresponding to therotational speed of the transmission input shaft 18. The transmission 14further illustratively includes a temperature sensor 35 positioned tosense an operating temperature of transmission fluid circulated withinthe transmission 14. The temperature sensor 35 is electrically connectedto a transmission fluid temperature input (TFT) of the control circuit30 via a signal path 36. The temperature sensor 35 may be conventionaland is configured to produce a temperature signal corresponding to theoperating temperature of the transmission fluid circulated within thetransmission 14.

The transmission 14 further includes a number, N, of electricallycontrollable actuators included within the electro-hydraulic controlsystem 24 that are each electrically connected to different one of acorresponding number of actuator control outputs, AC₁-AC_(N) of thetransmission control circuit 30 via corresponding signal paths 28 ₁-28_(N), wherein N may be any positive integer. The one or moreelectrically controllable actuators included within theelectro-hydraulic control system 24, examples of which will be describedhereinafter, are responsive to actuator control signals produced by thetransmission control circuit 30 on the corresponding signal paths 28₁-28 _(N) to control various operational features of the transmission14.

Illustratively, the transmission control circuit 30 ismicroprocessor-based, and includes a memory unit 32 having instructionsstored therein that are executable by the control circuit 30 to controloperation of the transmission 14 generally, and more specifically tocontrol operation of the electro-hydraulic control system 24. It will beunderstood, however, that this disclosure contemplates other embodimentsin which the transmission control circuit 30 is notmicroprocessor-based, but is configured to control operation of thetransmission 14 generally and operation of the electro-hydraulic system24 more specifically, based on one or more sets of hardwiredinstructions and/or software instructions stored in the memory unit 32.

Referring now to FIG. 3, a schematic diagram is shown of oneillustrative embodiment of the electro-hydraulic control system 24 ofFIG. 1. In the illustrated embodiment, the electro-hydraulic controlsystem 24 is roughly divided into separate control sections; a variatorcontrol section 56 comprising a variator trim control sub-system 56A, avariator actuator sub-system 56B and a variator switching sub-system56C, a clutch control section 58, and a clutch and variator pressure andfluid flow control section 98.

Referring specifically to the clutch and variator pressure and fluidflow control section 98, a conventional fluid pump 60 is configured tosupply transmission fluid, e.g., conventional transmission oil, to thevariator trim control section 56A, the variator switching and faultdetection section 56C and to the clutch control section 58 from a source64 of transmission fluid, e.g., a conventional transmission sump 64. Inone illustrative embodiment, the fluid pump 60 is a conventionalpositive-displacement pump that is driven by the drive shaft 16 of theengine 12 via the input shaft 18 of the transmission 14, and is sizedand configured to supply pressurized fluid from the sump 64 to a numberof friction control devices, e.g., clutches, and to the variator. In theillustrated embodiment, a fluid inlet of the fluid pump 60 is fluidlycoupled to the sump 64 via a fluid passageway 62. Illustratively, thetemperature sensor 35 is fluidly coupled to or carried by the sump 64such that the temperature signal produced by the sensor 35 correspondsto the temperature of transmission fluid in the sump 64, although thetemperature sensor 35 may alternatively be positioned or locatedelsewhere relative to the transmission 14.

A fluid outlet of the pump 60 is fluidly coupled via a clutch main fluidpassageway 65 to a fluid port and end of a dual pump pressure regulatorvalve 190, to a fluid outlet of a check ball valve 101, to a fluid inletof a variator trim valve 70, to a fluid port of a variator pressuremultiplex valve 220, to a control main fluid passageway 104 via aconventional flow reducer, to a fluid port of a conventional mainpressure regulator valve 180 and a fluid inlet of a main clutch pressurerelief valve 186, and to fluid ports of two trim valves 152 and 154included in the clutch control section 58. The clutch and variatorpressure and fluid flow control section 98 further includes anotherconventional fluid pump 100 configured to supply transmission fluid,e.g., conventional transmission oil, to the dual pump pressure regulatorvalve 190 and, under some operating conditions, to the fluid path 65 tothereby supplement the supply of fluid by the fluid pump 60. In oneillustrative embodiment, the fluid pump 100 is a conventionalpositive-displacement pump that is driven by the drive shaft 16 of theengine 12 via the input shaft 18 of the transmission 14, and is sizedand configured to supply pressurized fluid to a conventionaltransmission lubrication system. In the illustrated embodiment, a fluidinlet of the fluid pump 100 is fluidly coupled to the sump 64 via thefluid passageway 62. A fluid outlet of the pump 100 is fluidly coupledvia a fluid cooler/lube fluid passageway 102 to a fluid port of the dualpump pressure regulator valve 190 and to a fluid inlet of the check ballvalve 101. Under some operating conditions of the electro-hydrauliccontrol system 24, the dual pump pressure regulator valve 190 directsfluid supplied by the fluid pump 100 to a conventional cooler andlubrication sub-system 160 of the transmission 14 via a fluid path 162.In the illustrated embodiment, the fluid path 162 is fluidly coupled toa fluid inlet of a cooler relief valve 164 and to a fluid inlet of aconventional cooler 166. A fluid outlet of the cooler 166 is fluidlycoupled through a fluid filter 168 to a fluid port and end of a gearlubrication regulator valve 170 and to gear lubrication and variatorlubrication passageways 172 and 174 respectively. Further detailsrelating to the structure and operation of the clutch and variatorpressure and fluid flow control section 98 generally, and to thestructure and operation of the dual pump pressure regulator valve 190 inparticular, will be described in detail hereinafter.

The control main fluid passageway 104 is fluidly coupled to fluid inletsand fluid ports of the control main pressure regulator valve 180 and aconventional control main pressure relief valve 182, to a fluid inlet ofa conventional control main pressure accumulator valve 184, to controlmain inputs of actuators 154, 158, 164, 168, 85 and 87 and to fluidports of valves 152, 154, 162, 96, 82, 88 and 76. The control mainpassageway 104 supplies control main fluid to the foregoing actuatorsand valves.

Referring now to the variator trim control sub-system 56A of thevariator control section 56, a variator main fluid passageway 68 is fed,under certain operating conditions as described in detail hereinafter,by the clutch main fluid passageway 65 via the dual pump pressureregulator valve 190. The variator main fluid passageway 68 is fluidlycoupled to a fluid inlet of a variator trim valve 72 and to one end of avariator fault valve 76. The variator trim valve 72 includes an actuator84 that is electrically connected to the transmission control circuit 30via a signal path 28 ₂. Another fluid inlet of the variator trim valve72 is fluidly coupled to exhaust, and a fluid outlet of the variatortrim valve 72 is fluidly coupled to an end of the variator fault valve76 opposite the end to which the variator main fluid passageway iscoupled, and is also fluidly coupled through a conventional mode damper118, to a fluid port of the variator pressure multiplex valve 220.Another variator trim valve 70 includes an actuator 74 that iselectrically connected to the transmission control circuit 30 via asignal path 28 ₁. One fluid inlet of the variator trim valve 70 isfluidly coupled to the clutch main fluid passageway 65. Another fluidinlet of the variator trim valve 70 is fluidly coupled to exhaust, and afluid outlet of the variator trim valve 70 is fluidly coupled to anotherfluid port of the variator pressure multiplex valve 220. The actuators74 and 84 are illustratively conventional electronically actuatedsolenoids, and the trim valves 70 and 72 are illustrativelyvariable-bleed valves that supply variable-pressure transmission fluidbased on control signals produced by the transmission control circuit 30on the signal paths 28 ₁ and 28 ₂ respectively.

Under normal operating conditions, the variator pressure multiplex valve220 routes variator main fluid from the outlet of the mode damper 118 tothe variator switching sub-system 56C and routes the fluid outlet of thevariator trim valve 70 to an end chamber of the dual pump pressureregulator valve 190 such that under such normal operating conditions thevariator trim valve 72 controls the variator switching sub-system 56Cand the fluid pressures in the clutch main fluid passageway 65 and inthe endload passageway of the variator actuator control sub-system 56Bare modulated by the variator trim valve 70. Under other operatingconditions, e.g., during cold start and/or certain fault conditions, thevariator pressure multiplex valve 220 exhausts one end chamber of thedual pump pressure regulator valve 190 such that the dual pump regulatorvalve 190 regulates the fluid pressure in the clutch main fluidpassageway 65 (and thus the fluid pressures in the other main fluidpassageways) to a constant fluid pressure, and the variator pressuremultiplex valve 220 further routes fluid from the clutch main fluidpassageway 65 directly to the variator switching sub-system 56C suchthat under such other operating conditions the variator trim valve 70controls the variator switching sub-system 56C. Further details relatingto the structure and operation of the variator trim control sub-system56A are described in co-pending U.S. patent application Ser. No. ______,having attorney docket number ATP-0054-USP/46582-212954, the disclosureof which is incorporated herein by reference in its entirety.

Referring now to the variator actuator sub-system 56B of the variatorcontrol section 56, a fluid path 112 fluidly coupled to the variatorswitching sub-system 56C defines a variator high-side fluid passageway,S1, and a fluid path 116 also fluidly coupled to the variator switchingsubsection 56C defines a variator low-side fluid passageway, S2. In theembodiment illustrated in FIG. 3, the variator includes six actuators,50 ₁-50 ₆, e.g., conventional pistons, and the variator high-side fluidpassageway 112 is fluidly coupled to the high side of each such actuator50 ₁-50 ₆ via a corresponding conventional damper 122 ₁-122 ₆. Aconventional check valve 126 is interposed between the variatorhigh-side fluid passageway 112 and a fluid passageway 128. The variatorlow-side fluid passageway 116 is fluidly coupled to the low side of eachactuator 50 ₁-50 ₆ via a corresponding conventional damper 136 ₁-136 ₆,and another conventional check valve 140 is interposed between thevariator low-side fluid passageway 116 and the fluid passageway 128. Thefluid passageway 128 is fluidly coupled to an endload relief valve 130,which is further fluidly coupled between the high side and the low sideof the actuator 50 ₆. Further details relating to one illustrativestructure and method of operating the endload relief valve 130 areprovided in co-pending U.S. Patent Application Ser. No. 61/287,020,having Attorney Docket No. 46582-209632 (ATP-0047-USP), the disclosureof which is incorporated herein by reference in its entirety.

The fluid passageway 128 is further fluidly coupled to another fluidpassageway 132, and an endload port or passageway 135 is fluidly coupledto another fluid passageway 134. In the state of the variator multiplexvalve 220 illustrated in FIG. 3, i.e., stroked, the fluid passageway 132is fluidly coupled via the variator pressure multiplex valve 220 to thefluid passageway 134 such that the fluid pressure within the endloadport or passageway 135 is supplied by the fluid passageway 128.Generally, the fluid pressure in the endload port or passageway 135 isthe pressure load on the variator disks required to keep the variatordisks from slipping. Under normal operating conditions, such asillustrated in FIG. 3, the variator pressure multiplex valve 220 fluidlycouples the endload port or passageway 135 directly to the fluidpassageway 128 such that the fluid pressure in the endload fluidpassageway 128 is modulated by the fluid pressures in S1 and S2. Underother operating conditions, e.g., cold start and certain faultconditions, the variator pressure multiplex valve 220 routes a fluid ata fixed pressure, e.g., clutch main fluid in the clutch main fluidpassageway 65, to the endload fluid port or passageway 135 via the fluidpassageway 134, as is described in greater detail in co-pending U.S.patent application Ser. No. ______, having attorney docket numberATP-0054-USP/46582-212954.

A variator fault valve 76 is fluidly coupled between the variator mainfluid passageway 68 at one end and the fluid outlet of the variator trimvalve 72 at its opposite end. The variator fault valve 76 illustrativelyincludes a spool 142 which is responsive to a difference in pressurebetween the variator main fluid passageway 68 and the fluid outlet ofthe variator trim valve 72 to determine whether a variator fault exists.In the embodiment illustrated in FIG. 3, for example, if the fluidpressure in the variator main fluid passageway 68 is sufficientlygreater than that in the fluid outlet of the variator trim valve 72, thespool 142 is forced upwardly and thereby fluidly couples the exhaustbackfill fluid passageway (EB) 108 to the fluid passageway 144. This isthe position of the spool 142 illustrated in FIG. 3. If instead thefluid pressure in the fluid outlet of the variator trim valve 72 issufficiently greater than that in the variator main fluid passageway 68,the spool 142 is forced downwardly and thereby fluidly couples thecontrol main (COM) fluid passageway 104 to the fluid passageway 144.Illustratively, the variator fault valve 76 is designed to have aspecified amount of hysteresis between the two extreme positions of thespool 142, and in one embodiment the hysteresis is approximately 15-20%such that the differential pressure between variator main fluidpassageway 68 and the fluid outlet of the variator trim valve 72 must begreater than about 15-20% before the spool 142 changes position. Thoseskilled in the art will appreciate that this hysteresis value isprovided only by way of example and that other hysteresis values, or nohysteresis value, may alternatively be used.

Referring now to the variator switching sub-system 56C of the variatorcontrol section 56, a pair of variator control valves 82 and 88 eachinclude an actuator 85 and 95 respectively that is electricallyconnected to the transmission control circuit 30 via a signal path 28 ₃and 28 ₄ respectively. In the illustrated embodiment, the actuators 85and 95 are illustratively conventional electronically actuatedsolenoids. The actuators 85 and 95 are responsive to control signalsproduced by the transmission control circuit 30 on the signal paths 28 ₃and 28 ₄ respectively to selectively control the valves 82 and 88 tothereby selectively supply S1 and S2 fluid pressures provided by thevariator trim valve 72 under normal operating conditions, or provided bythe variator trim valve 70 under other operating conditions, e.g., coldstart and certain fault conditions, to the variator actuator sub-system56B of the variator control section 56. Further details relating to thestructure and operation of the variator control valves 82 and 88 aredescribed in co-pending U.S. patent application Ser. No. ______, havingattorney docket number ATP-0052-USP/46582-212952, the disclosure ofwhich is incorporated herein by reference in its entirety.

Referring now to the clutch control section 58, the clutch main fluidpassageway 65 is illustratively fluidly coupled to each of a pair ofclutch trim valves 150 and 152 which together define a trim system. Theclutch trim valves 150 and 152 each illustratively include an actuator154 and 158 respectively that is electrically connected to thetransmission control circuit 30 via a signal path 28 ₅ and 28 ₆respectively. One control fluid inlet of each of the clutch trim valves150 and 152 is fluidly coupled to the control main fluid passageway 104,and another control fluid inlet of each clutch trim valve 150 and 152 isfluidly coupled to exhaust. In the illustrated embodiment, the actuators154 and 158 are illustratively conventional electronically actuatedsolenoids. Fluid outlets of each of the clutch trim valves 150 and 152are fluidly coupled to fluid inlets of each of a pair of clutch controlvalves 162 and 96. The clutch trim valves 150 and 152 are eachconfigured to selectively, i.e., under the control of the transmissioncontrol circuit 30 via signals produced by the transmission controlcircuit 30 on the signal paths 28 ₅ and 28 ₆ respectively, fluidlycouple the clutch main fluid passageway 65 to the clutch control valves162 and 96.

The clutch control valves 162 and 96 each illustratively include anelectronic actuator, e.g., an electrically controlled solenoid, 164 and168 respectively that is electrically connected to the transmissioncontrol circuit 30 via a signal path 28 ₇ and 28 ₈ respectively. Onecontrol fluid inlet of each clutch control valve 162 and 96 is fluidlycoupled to the control main, COM, fluid passageway 104, and anothercontrol fluid inlet is fluidly coupled to exhaust. The clutch controlvalve 96 is further fluidly coupled directly to the C2 clutch fluid path25 ₂, and clutch main fluid or exhaust backfill is selectively appliedto the C2 clutch via the fluid path 25 ₂ via various combinations ofstates of the actuators 154, 158, 164 and 168. The clutch control valve162 is further fluidly coupled directly to each of the C1 and C3 clutchfluid paths 25 ₁ and 25 ₃, and clutch main fluid or exhaust backfill isselectively routed through the clutch control valve 162 to the C1 clutchvia the fluid passageway 25 ₁ or to the C3 clutch via the fluidpassageway 25 ₃ via various combinations of states of the actuators 154,158, 164 and 168. The clutches C1-C3 are thus selectively activated,i.e., engaged, and deactivated, i.e., disengaged, based on the operatingstates of the actuators 154, 158, 164 and 168 of the clutch trim valves150 and 152 and the clutch control valves 162 and 96 respectively, byselectively routing clutch main fluid and exhaust backpressure throughthe control valves 162 and 96 to the various clutches C1-C3.

Further details relating to the structure and operation of the clutchcontrol subsection 58 are provided in co-pending U.S. Patent ApplicationSer. No. 61/287,031, having Attorney Docket No. 46582-209546(ATP-0043-USP), and in co-pending U.S. Patent Application Ser. No.61/287,038, having Attorney Docket No. 46582-209547 (ATP-0044-USP), thedisclosures of which are both incorporated herein by reference in theirentireties.

In the illustrated embodiment, sensors are operatively positionedrelative to the variator fault valve 76, the variator control valve 88,the clutch trim valve 154 and each of the clutch control valves 162 and96 to enable monitoring of the operating states of each of the valves76, 88, 154, 162 and 96 and to further monitor certain transmissionoperating state faults. In one illustrative embodiment, such sensors areprovided in the form of conventional pressure switches, although it willbe understood that a conventional pressure sensor may be substituted forany one or more of the pressure switches. In the illustrated embodiment,for example, a pressure switch 146 is fluidly coupled to a fluid port ofthe variator control valve 88, and is electrically connected to thetransmission control circuit 30 via a signal path 26 ₁. Another pressureswitch 148 is fluidly coupled to the fluid port 144 of the variatorfault valve 76, and is electrically connected to the transmissioncontrol circuit 30 via a signal path 26 ₂. Still another pressure switch184 is fluidly coupled to a fluid port of the clutch control valve 162,and is electrically connected to the transmission control circuit 30 viaa signal path 26 ₃. Yet another pressure switch 188 is fluidly coupledto a fluid port of the clutch control valve 96, and is electricallyconnected to the transmission control circuit 30 via a signal path 26 ₄.A further pressure switch 186 is fluidly coupled to a fluid port of theclutch trim valve 154, and is electrically connected to the transmissioncontrol circuit 30 via a signal path 26 ₅.

Signals produced by the pressure switches 146, 148, 184, 188 and 186 areprocessed by the transmission control circuit 30 to allow monitoring anddiagnosis by the transmission control circuit 30 of the states of thesepressure switches and thus the operating states of the each of thevalves 76, 88, 154, 162 and 96. For example, in the embodimentillustrated in FIG. 3, the pressure switch 148 is configured to producea signal corresponding to the state, e.g., normal or variator fault, ofthe variator fault valve 76. If the fluid pressure in the variator mainfluid passageway 68 is sufficiently greater than that in the fluidoutlet of the variator trim valve 72 such that the spool 142 is forcedupwardly and thereby fluidly couples the exhaust backfill fluidpassageway (EB) 108 to the fluid passageway 144, as illustrated in FIG.3, this corresponds to normal operation of the variator in which thepressure switch 148 produces a low or logical “0” signal. If instead thefluid pressure in the fluid outlet of the variator trim valve 72 issufficiently greater than that in the variator main fluid passageway 68,the spool 142 is forced downwardly (not shown in the FIGS) which causesthe spool 142 to fluidly couple the control main (COM) fluid passageway104 to the fluid passageway 144. This corresponds to a variator faultconditions and the pressure switch 148 under such a variator faultcondition switches to a high or logical “1” state. Thus, under normaloperating conditions the pressure switch 148 produces a low or “0”signal, and under variator fault conditions the pressure switch 148produces a high or “1” signal. The memory 32 of the transmission controlcircuit 30 Illustratively includes instructions stored therein that areexecutable by the control circuit 30 to process the signal produced bythe pressure switch 148 to determine whether the variator is operatingnormally or whether a variator fault exists.

Further details relating to diagnosis of the signals produced by thepressure switch 146 will be described hereinafter. Further detailsrelating to diagnosis of the signals produced by the pressure switches184, 186 and 188 are described in co-pending U.S. Patent ApplicationSer. No. 61/287,031, having Attorney Docket No. 46582-209546(ATP-0043-USP).

Referring now to FIGS. 4-8, further details relating to the structureand operation of the clutch and variator pressure and fluid flow controlsection 98 are illustrated. In the embodiment illustrated in FIGS. 4-8,like reference numbers are used to identify like components of thesection 98 illustrated in FIG. 3. However, for ease of illustration andfacilitation of understanding of the section 98, some of the connectionsof various fluid passageways are not shown and/or are truncated, andsome of the sub-systems fluidly coupled to the clutch and variatorpressure and fluid flow control section 98 are shown in block form. Forexample, in FIGS. 4-8 the clutch main fluid passageway 65 is shownfluidly connected to one end of the dual pump pressure regulator valve190 via a fluid passageway 203 and through a conventional flow reducer,to the variator pressure multiplex valve 220 (VPM) represented in blockform, to the variator switching sub-system 56C also represented in blockform and to the clutch control section 58 also represented in blockform, and is also fluidly coupled to the dual pump pressure regulatorvalve 190 via a fluid passageway 222 through a conventional flow reducerand a fluid passageway 224, and is fluidly connected to a fluid inlet ofthe variator trim valve 70 via a fluid passageway 226. Fluid connectionsand/or couplings between the clutch main fluid passageway 65 and otherdevices and/or sections and/or subsystems illustrated in FIG. 3 areomitted from FIGS. 4-8. Further, the various components of thelubrication and cooling sub-system 160 illustrated in FIG. 3 are shownin FIGS. 4-8 as a single block 160.

The dual pump pressure regulator valve 190 includes a spool 200 thataxially translates under pressure within the valve 190, e.g., within aconventional valve housing (not shown). The spool 200 defines a numberof lands 204, 206, 208, 210 and 212 consecutively and sequentiallypositioned along the spool 200 from one end 202 to an opposite end 214.The end of the valve 190 in which the end 202 of the spool 200translates is fluidly coupled via a conventional flow reducer to theclutch main fluid passageway 65 by the fluid passageway 203. A spoolbase 216 is positioned within and at a terminal end of a spring pocket230, and a conventional valve spring 218 engages and extends between theend 214 of the spool 200 and the spool base 216. The valve spring 218 iscompressed and therefore exerts a spring bias or spring force betweenand against the spool base 216 and the end 214 of the spool 200. Becausethe position of the spool base 216 is fixed at one end of the springpocket 230, the spool 200 is under bias of the valve spring 218 in thedirection of the spool end 202. The spring pocket 230 of the dual pumppressure regulator valve 190 is further fluidly coupled to the variatorpressure multiplex valve 220 via a fluid passageway 229, and thevariator pressure multiplex valve 220 is fluidly coupled to a fluidoutlet of the variator trim valve 70 via a fluid passageway 228. Thefluid passageway 162 fluidly connected to the lubrication and coolingsub-system 160 is fluidly coupled to the dual pump pressure regulatorvalve 190 via two separate fluid passageways 232 and 234.

As described hereinabove, the variator trim valve 70 is illustratively aconventional variable-bleed valve that receives fluid at its fluid inletfrom the clutch main fluid passageway 65 and supplies variable-pressuretransmission fluid at its outlet based on a control signal produced bythe transmission control circuit 30 on the signal path 28 ₁. The fluidoutlet of the variator trim valve 70 is fluidly coupled to the variatorpressure multiplex valve 220 via the fluid passageway 229. Under certainpredefined operating conditions of the transmission 14, such asillustrated and will be described with respect to FIG. 8, the variatorpressure multiplex valve 220 fluidly couples a fixed reference pressureto the fluid passageway 229 such that the fixed reference pressure issupplied to the spring pocket 230 of the dual pump pressure regulatorvalve 190 under such predefined operating conditions as will bedescribed in greater detail hereinafter with respect to FIG. 8. However,under normal operating conditions of the transmission 14, such asillustrated and will be described with respect to FIGS. 4-7, thevariator pressure multiplex valve 220 fluidly couples the fluidpassageway 229 to the fluid passageway 228 such that thevariable-pressure transmission fluid produced by the variator trim valve70 at its fluid outlet is supplied to the spring pocket 230 of the dualpump pressure regulator valve 190. Under such normal operatingconditions, the position of the spool 200 within the dual pump pressureregulator valve 190 is defined by the fluid pressure at the end 202 ofthe spool 200, the fluid pressure at the opposite end 214 of the spool200 and the biasing force of the valve spring 218. The position of thespool 200 within the dual pump pressure regulator valve 190 under normaloperating conditions of the transmission 14 is thus a function of theflow rate, and hence the pressure, of transmission fluid supplied to theclutch main fluid passageway 65, the pressure of fluid supplied by thevariator trim valve 70 to the spring pocket 230 of the valve 190 and thebiasing force of the valve spring 218. The fluid pressure within theclutch main fluid passageway 65 is generally variable, e.g., betweenapproximately 200 and 800 psi, as a function of the flow rate of fluidsupplied by the pump 60, and under some operating conditions the flowrate of fluid supplied by the pump 100, the pressure of fluid suppliedby the variator trim valve 70 to the spring pocket 230 of the valve 190and the biasing force of the spring 218.

Referring now specifically to FIG. 4, one operating position of the dualpump pressure regulator valve 190, i.e., one operating position of thespool 200 within the valve 190, is shown. In FIG. 4, the end 202 of thespool 200 is positioned at or adjacent to the terminal end of the fluidpassageway 203. This position of the valve 190, i.e., of the spool 200within the valve 190, is illustratively characterized by low rotationalspeeds of the input shaft of the transmission 14 which drives the pumps60 and 100, high transmission operating temperatures such that thetransmission fluid has low viscosity and is therefore most likely toleak through and around actuators and friction engagement devices andhigh transmission fluid flow demands from the clutch control section 58.Under such operating conditions, the fluid pressure supplied by thevariator trim valve 70 to the spring pocket 230 of the dual pumppressure regulator valve 190 is controlled by the control circuit 30such that the combined forces of this fluid pressure, the biasing forceof the valve spring 218 and the fluid pressure applied to the end 202 ofthe spool 200 position the spool 200 to the fully unstroked position;i.e., with the end 202 of the spool 200 at or adjacent to the terminalend of the fluid passageway 203. In this position, the land 208 blocksthe fluid passageway 68 from the fluid passageway 224 such thattransmission fluid in the clutch main fluid passageway 65 is blockedfrom, and therefore is not supplied to, the variator control sub-system56C. Additionally, the land 208 blocks the fluid passageway 232 from thefluid passageway 224 and the land 210 blocks the fluid passageway 234from the fluid passageway 102 such that transmission fluid in the clutchmain fluid passageway 65 is blocked from, and therefore is not suppliedto, the lubrication and cooling sub-system 160 and transmission fluid inthe fluid passageway 102 is blocked from, and therefore is not suppliedto, the lubrication and cooling sub-system 160.

The ball check valve 101 has an inlet fluidly coupled to the fluidpassageway 102 and an outlet fluidly coupled to the clutch main fluidpassageway 65. The ball check valve 101 defines a pressure thresholdbetween its fluid inlet and its fluid outlet above which the ball 103 isdisplaced such that the valve 101 opens and allows fluid flow from itsfluid inlet through its fluid outlet. In one illustrative embodiment,this pressure threshold value is approximately 200 psi, although thevalve 101 may be designed or selected to define other pressure thresholdvalues. In any case, under operating conditions in which the lands 208and 210 block the fluid passages 232 and 234 respectively as justdescribed, fluid pressure within the fluid passageway 102 increasesrapidly due to the operation of the pump 100 until the pressurethreshold value of the check ball valve 101 is exceeded and transmissionfluid supplied by the pump 100 flows through the check ball valve 101into the clutch main fluid passageway 65. Thus, under operatingconditions characterized by low transmission input speeds resulting inlow transmission fluid flow through the clutch main fluid passageway 65,high transmission fluid temperature and high flow demand fortransmission fluid in the clutch main fluid passageway 65, the dual pumppressure regulator valve 190 controls the fluid pressure in the springpocket 230 of the valve 190 to position the spool 200 to block the flowof transmission fluid to the variator control sub-system 56C and to thelubrication and cooling system 160, and the check ball valve 101 isopened as a result of the pressure difference between the fluidpassageways 102 and 65 exceeding the pressure threshold value of thevalve 101, as illustrated in FIG. 4, such that the pumps 60 and 100together supply transmission fluid via the clutch main fluid passageway65 only to the clutch control section 58 of the electro-hydrauliccontrol system 24.

The memory 32 of the control circuit 30 illustratively has instructionsstored therein that are executable by the control circuit 30 to controloperation of the variator trim valve 70 under the operating conditionsjust described to position the spool 200 of the dual pump pressureregulator valve 190 in the position illustrated in FIG. 4. In oneembodiment, the low fluid flow condition in the clutch main fluidpassageway 65 is determined by the control circuit 30 by monitoring therotational speed of the input shaft 18 of the transmission, e.g., bymonitoring the speed signal produced by the transmission input speedsensor 33 on the signal path 34, or by receiving the value of therotational speed of the output shaft 16 of the power plant from acontrol circuit associated with the power plant 12, and determiningwhether the rotational speed of the input shaft 18 of the transmission14 is below an emergency low speed threshold value.

Illustratively, the instructions stored in the memory 32 further includeconventional instructions executable by the control circuit 30 tocorrelate the transmission input shaft speed value, e.g., via one ormore stored tables, to a flow rate of fluid, and/or the fluid pressure,within the fluid passageway 65. Such instructions may furtherillustratively include conventional instructions to include in theeffect of fluid operating temperature on the correlation between thetransmission input shaft speed and the flow rate and/or pressure offluid within the fluid passageway 65, which information may be obtainedfrom the transmission fluid temperature sensor 35. In one illustrativeembodiment, the emergency low speed threshold value may be an RPM valuethat correlates to a corresponding emergency low speed clutch main fluidpressure of approximately 200 psi or an emergency low transmission fluidflow rate of approximately 7 gpm, although other threshold value(s) mayalternatively be used.

In one embodiment, the high transmission fluid temperature condition isdetermined by the control circuit 30 by monitoring the temperaturesignal produced by the transmission fluid temperature sensor 35 on thesignal path 36, and/or by estimating the temperature of the transmissionfluid via one or more known temperature estimation algorithms, anddetermining whether the temperature of the transmission fluid is above atemperature threshold value. In one illustrative embodiment, thetemperature threshold value may be approximately 120 degrees C.,although other threshold value(s) may alternatively be used.

The biasing force of the spring 218 in the spring pocket 230 of thevalve 190 is known and illustratively stored in the memory 32 of thecontrol circuit 30. The instructions stored in the memory 32 of thecontrol circuit 30 further include conventional instructions executableby the control circuit 30 to control operation of the various frictionengagement devices, e.g., the clutches C1, C2 and C3 in the illustratedembodiment, and the control circuit 30 therefore has knowledge of thetransmission fluid flow demand by such friction engagement devicesand/or other transmission fluid controlled components and sub-systems.In one illustrative embodiment, the high transmission fluid flow demandcondition is determined by the control circuit 30 by determining thecurrent transmission fluid flow demanded by the various components ofthe transmission, and determining whether the current transmission fluidflow demand is above a fluid flow demand threshold. In one illustrativeembodiment, the fluid flow demand threshold may be approximately 7 gpm,although other threshold value(s) may alternatively be used.

In the illustrated embodiment, the instructions stored in the memory 32further include instructions executable by the control circuit 30 tomonitor the rotational speed of the input shaft 18 of the transmission,monitor the temperature of the transmission fluid and monitor thecurrent transmission fluid flow demand, and to modulate the controlsignal supplied to the actuator 74 of the variator trim valve 70 on thesignal path 281 such that the valve 70 supplies a fluid pressure to thespring pocket 230 that positions the spool 200 in the positionillustrated in FIG. 4 if the rotational speed of the transmission inputshaft is below the emergency low speed threshold, the temperature of thetransmission fluid is above the temperature threshold and thetransmission fluid flow demand is above the fluid flow demand threshold.The fluid pressure required to be supplied by the variator trim valve 70to the spring pocket 230 of the dual pump pressure regulator valve 190to position the spool 200 in the position illustrated in FIG. 4 is aconventional function of the current fluid pressure in the clutch mainfluid passageway 65, which is determined from the current rotationalspeed of the input shaft 18 of the transmission 14 as describedhereinabove, the biasing force of the valve spring 218, which is knownand stored in the memory 32, and the area of the end face 202 of thespool 200, which is also known and can be stored in the memory 32. Theinstructions stored in the memory 32 thus further include instructionsexecutable by the control circuit 30 to control the spool 200 to theposition illustrated in FIG. 4, under appropriate operating conditionsof the transmission 14 as just described, by computing the fluidpressure required to be supplied to the spring pocket 230 of the valve190 to position the spool 200 in the position illustrated in FIG. 4 as afunction of the fluid pressure in the clutch main fluid passageway 65,the biasing force of the valve spring 218 and the area of the end 202 ofthe spool 200, computing the control signal required to be applied tothe actuator 74 to cause the variator trim valve 70 to supply thecomputed fluid pressure to the spring pocket 230 of the valve 190, andsupplying the computed control signal to the actuator 74 via the signalpath 28 ₁. Illustratively, the instructions stored in the memory 32 mayfurther include instructions executable by the control circuit 30 tomaintain the dual pump pressure regulator valve 190 in the positionillustrated in FIG. 4 for only a predefined time period, after which thecontrol circuit 30 is operable to move the spool 200 to a position inwhich fluid is supplied, at least temporarily, to the variator switchingsub-system 56C and/or to the lubrication and cooling fluid sub-system160.

Referring now to FIG. 5, another operating position of the dual pumppressure regulator valve 190, i.e., another operating position of thespool 200 within the valve 190, is shown. In FIG. 5, the end 202 of thespool 200 is positioned away from the terminal end of the fluidpassageway 203, i.e., to the right of the terminal end of the fluidpassageway 203 in FIG. 5. This position of the valve 190, i.e., of thespool 200 within the valve 190, is illustratively characterized by thesame operating conditions just described with respect to FIG. 4 exceptthat the rotational speed of the input shaft of the transmission 14 isgreater than the emergency low speed threshold but less than another lowspeed threshold that is greater than the emergency low speed threshold.

Under such operating conditions characterized by low transmission fluidflow through the clutch main fluid passageway 65 resulting from therotational speed of the transmission input shaft 18 being greater thanthe emergency low speed threshold but less than another low speedthreshold, high transmission fluid temperature and high flow demand fortransmission fluid in the clutch main fluid passageway 65, the fluidpressure supplied by the variator trim valve 70 to the spring pocket 230of the dual pump pressure regulator valve 190 is controlled by thecontrol circuit 30 such that the combined forces of this fluid pressure,the biasing force of the valve spring 218 and the fluid pressure appliedto the end 202 of the spool 200 position the spool 200 to the positionillustrated in FIG. 5 with the end 202 of the spool 200 moved away fromthe terminal end of the fluid passageway 203. In this position, the land208 moves past the fluid passageway 68 such that the fluid passageway224 fluidly connects the clutch main fluid passageway 65 to the variatormain fluid passageway 68 so that transmission fluid in the clutch mainfluid passageway 65 is supplied to the variator control sub-system 56C.In the position of the spool 200 illustrated in FIG. 5, however, theland 208 continues to block the fluid passageway 232 from the fluidpassageway 224 and the land 210 continues to block the fluid passageway234 from the fluid passageway 102 such that transmission fluid in theclutch main fluid passageway 65 is blocked from, and therefore is notsupplied to, the lubrication and cooling sub-system 160 and transmissionfluid in the fluid passageway 102 is blocked from, and therefore is notsupplied to, the lubrication and cooling sub-system 160.

Because the lands 208 and 210 continue to block the fluid passages 232and 234 respectively as just described, the difference in fluid pressurewithin the fluid passageways 102 and 65 will again exceed the pressurethreshold value of the check ball valve 101, and transmission fluidsupplied by the pump 100 therefore flows through the check ball valve101 into the clutch main fluid passageway 65 as described hereinabovewith respect to FIG. 4. Thus, under operating conditions characterizedby transmission input speeds between the emergency low speed thresholdand another low speed threshold that is greater than the emergency lowspeed threshold that results in low transmission fluid flow, but greaterthan that described with respect to FIG. 4, through the clutch mainfluid passageway 65, high transmission fluid temperature and high flowdemand for transmission fluid in the clutch main fluid passageway 65,the dual pump pressure regulator valve 190 blocks the flow oftransmission fluid to the lubrication and cooling system 160 but allowstransmission fluid flow to the variator switching sub-system 56C, andthe check ball valve 101 is opened as a result of the pressuredifference between the fluid passageways 102 and 65, such that the pumps60 and 100 together supply transmission fluid via the clutch main fluidpassageway 65 to the clutch control section 58 and also to the variatorswitching sub-system 56C of the electro-hydraulic control system 24.

Control of the dual pump pressure regulator valve 190 by the controlcircuit 30 to the position illustrated in FIG. 5 illustratively occursas described hereinabove with respect to FIG. 4 except that rather thancomparing the current transmission input speed to the emergency lowspeed threshold the control circuit 30 compares the current transmissioninput sped to the emergency low speed threshold and another low speedthreshold and controls the spool 200 to the position illustrated in FIG.5 only if the current transmission input speed is between these two lowspeed thresholds. Thus, in the illustrated embodiment, the instructionsstored in the memory 32 further include instructions executable by thecontrol circuit 30 to monitor the rotational speed of the input shaft 18of the transmission, monitor the temperature of the transmission fluidand monitor the current transmission fluid flow demand, and to modulatethe control signal supplied to the actuator 74 of the variator trimvalve 70 on the signal path 281 such that the valve 70 supplies a fluidpressure to the spring pocket 230 that positions the spool 200 in theposition illustrated in FIG. 5 if the rotational speed of thetransmission input shaft is greater than the emergency low speedthreshold but less than another low speed threshold that is greater thanthe emergency low speed threshold, the temperature of the transmissionfluid is above the temperature threshold and the transmission fluid flowdemand is above the fluid flow demand threshold. The fluid pressurerequired to be supplied by the variator trim valve 70 to the springpocket 230 of the dual pump pressure regulator valve 190 to position thespool 200 in the position illustrated in FIG. 5 is as describedhereinabove with respect to FIG. 4. Illustratively, the instructionsstored in the memory 32 may further include instructions executable bythe control circuit 30 to maintain the dual pump pressure regulatorvalve 190 in the position illustrated in FIG. 5 for only a predefinedtime period, after which the control circuit 30 is operable to move thespool 200 to a position in which fluid is supplied, at leasttemporarily, to the lubrication and cooling fluid sub-system 160.

Referring now to FIG. 6, yet another operating position of the dual pumppressure regulator valve 190, i.e., another operating position of thespool 200 within the valve 190, is shown. In FIG. 6, the end 202 of thespool 200 is positioned further away from the terminal end of the fluidpassageway 203, i.e., to the further to the right of the terminal end ofthe fluid passageway 203 such that the position of the end 202 of thevalve in FIG. 5 is between that illustrated in FIGS. 4 and 6. Thisposition of the valve 190, i.e., of the spool 200 within the valve 190,is illustratively characterized by an adequate flow of transmissionfluid through the clutch main fluid passageway 65 resulting fromrotational speed of the input shaft 18 of the transmission greater thanthe low speed threshold used as the upper threshold to position thespool 200 as shown in FIG. 5 and transmission fluid temperature that isless than the temperature threshold value.

Under such operating conditions characterized by adequate transmissionfluid flow through the clutch main fluid passageway 65 resulting fromthe rotational speed of the transmission input shaft 18 being greaterthan the low speed threshold used as the upper speed threshold forcontrolling the valve 190 to the position illustrated in FIG. 5 andtransmission fluid temperature less than the temperature thresholdvalue, the fluid pressure supplied by the variator trim valve 70 to thespring pocket 230 of the dual pump pressure regulator valve 190 iscontrolled by the control circuit 30 such that the combined force ofthis fluid pressure, the biasing force of the valve spring 218 and thefluid pressure applied to the end 202 of the spool 200 position thespool 200 to the position illustrated in FIG. 6 with the end 202 of thespool 200 moved further away from the terminal end of the fluidpassageway 203 than that illustrated in FIG. 5. In this position, thefluid passageway 224 continues to fluidly connect the clutch main fluidpassageway 65 to the variator main fluid passageway 68 so thattransmission fluid in the clutch main fluid passageway 65 is supplied tothe variator control sub-system 56C. The land 208 also continues toblock the fluid passageway 232 from the fluid passageway 224, andtransmission fluid in the clutch main fluid passageway 65 thereforecontinues to be blocked from, and therefore is not supplied to, thelubrication and cooling sub-system 160. However, with the spool 200 inthe position illustrated in FIG. 6, the land 210 no longer blocks thefluid passageway 234 from the fluid passageway 102 such that the valve190 fluidly connects the fluid passageway 234 to the fluid passageway102 so transmission fluid supplied to the fluid passageway 102 by thepump 100 is supplied to the lubrication and cooling sub-system 160.Furthermore, because the land 210 no longer block the fluid passageway234 from the fluid passageway 102, the difference in fluid pressurewithin the fluid passageways 102 and 65 no longer exceeds the pressurethreshold value of the check ball valve 101, and the check ball 103therefore closes the valve 101 such that transmission fluid supplied bythe pump 100 does not flow through the check ball valve 101 into theclutch main fluid passageway 65. Thus, under operating conditionscharacterized by transmission input speeds greater than the low speedthreshold and transmission fluid temperature less than the temperaturethreshold value, the dual pump pressure regulator valve 190 blocks theflow of transmission fluid from the clutch main fluid passageway 65 tothe lubrication and cooling sub-system 160, but allows transmissionfluid flow supplied only by the pump 60 to the clutch main fluidpassageway 65 to flow to the clutch control section 58 and to thevariator switching sub-system 56C, and further allows transmission fluidflow supplied only by the pump 100 to flow from the fluid passageway 102to the lubrication and cooling sub-system 160.

Control of the dual pump pressure regulator valve 190 by the controlcircuit 30 to the position illustrated in FIG. 6 illustratively occursas described hereinabove with respect to FIGS. 4 and 5 except that thespool 200 is controlled by the control circuit 30 to the positionillustrated in FIG. 6 only when the current transmission input speed isgreater than the low speed threshold that was used as the upper speedthreshold when controlling the spool to the position illustrated in FIG.5 and the temperature of the transmission fluid is less than thetemperature threshold value. Thus, in the illustrated embodiment, theinstructions stored in the memory 32 further include instructionsexecutable by the control circuit 30 to monitor the rotational speed ofthe input shaft 18 of the transmission and monitor the temperature ofthe transmission fluid, and to modulate the control signal supplied tothe actuator 74 of the variator trim valve 70 on the signal path 281such that the valve 70 supplies a fluid pressure to the spring pocket230 that positions the spool 200 in the position illustrated in FIG. 6if the rotational speed of the transmission input shaft is greater thanthe low speed threshold that is greater than the emergency low speedthreshold and the temperature of the transmission fluid is less than thetemperature threshold. The fluid pressure required to be supplied by thevariator trim valve 70 to the spring pocket 230 of the dual pumppressure regulator valve 190 to position the spool 200 in the positionillustrated in FIG. 6 is as described hereinabove with respect to FIG.4.

Referring now to FIG. 7, still another operating position of the dualpump pressure regulator valve 190, i.e., another operating position ofthe spool 200 within the valve 190, is shown. In FIG. 7, the end 202 ofthe spool 200 is positioned still further away from the terminal end ofthe fluid passageway 203, i.e., to the further to the right of theterminal end of the fluid passageway 203 such that the position of theend 202 of the valve in FIG. 6 is between that illustrated in FIGS. 5and 7. This position of the valve 190, i.e., of the spool 200 within thevalve 190, is illustratively characterized by high cooling demand duringotherwise high or adequate flow of transmission fluid through the clutchmain fluid passageway 65, which results from rotational speed of theinput shaft 18 of the transmission greater than the low speed thresholdused as the upper threshold to position the spool 200 as shown in FIG. 5and transmission fluid temperature that is greater than the temperaturethreshold value.

Under such operating conditions, the fluid pressure supplied by thevariator trim valve 70 to the spring pocket 230 of the dual pumppressure regulator valve 190 is controlled by the control circuit 30such that the combined force of this fluid pressure, the biasing forceof the valve spring 218 and the fluid pressure applied to the end 202 ofthe spool 200 position the spool 200 to the position illustrated in FIG.7 with the end 202 of the spool 200 moved further away from the terminalend of the fluid passageway 203 than that illustrated in FIG. 6. In thisposition, the fluid passageway 224 continues to fluidly connect theclutch main fluid passageway 65 to the clutch control section 58 and tothe variator main fluid passageway 68 so that transmission fluid in theclutch main fluid passageway 65 is supplied to the clutch controlsection 58 and to the variator control sub-system 56C. The fluidpassageway 234 likewise continues to be fluidly connected to the fluidpassageway 102 so that transmission fluid supplied by the pump 100 tothe fluid passageway 102 continues to be supplied to the lubrication andcooling sub-system 160. However, with the spool 200 in the positionillustrated in FIG. 6, the land 208 no longer blocks the fluidpassageway 224 from the fluid passageway 234 such that the valve 190fluidly connects the fluid passageway 234 to the fluid passageway 224 sotransmission fluid supplied to the control main fluid passageway 65 bythe pump 60 is supplied to the lubrication and cooling sub-system 160 tosupplement the flow of transmission fluid supplied to the lubricationand cooling sub-system 160 by the pump 100. The check ball valve 101remains closed in the position of the spool 200 illustrated in FIG. 7such that transmission fluid supplied by the pump 100 does not flowthrough the check ball valve 101 into the clutch main fluid passageway65. Thus, under operating conditions characterized by transmission inputspeeds greater than the low speed threshold and transmission fluidtemperature greater than the temperature threshold value, the dual pumppressure regulator valve 190 allows transmission fluid flow suppliedonly by the pump 60 to the clutch main fluid passageway 65 to flow tothe clutch control section 58, the variator switching sub-system 56C andthe lubrication and cooling sub-system 160, and further allowstransmission fluid flow supplied only by the pump 100 to flow from thefluid passageway 102 to the lubrication and cooling sub-system 160.

Control of the dual pump pressure regulator valve 190 by the controlcircuit 30 to the position illustrated in FIG. 7 illustratively occursas described hereinabove with respect to FIGS. 4-6 except that the spool200 is controlled by the control circuit 30 to the position illustratedin FIG. 7 only when the current transmission input speed is greater thanthe low speed threshold that was used as the upper speed threshold whencontrolling the spool to the position illustrated in FIG. 5 and thetemperature of the transmission fluid is greater than the temperaturethreshold value. Thus, in the illustrated embodiment, the instructionsstored in the memory 32 further include instructions executable by thecontrol circuit 30 to monitor the rotational speed of the input shaft 18of the transmission and monitor the temperature of the transmissionfluid, and to modulate the control signal supplied to the actuator 74 ofthe variator trim valve 70 on the signal path 281 such that the valve 70supplies a fluid pressure to the spring pocket 230 that positions thespool 200 in the position illustrated in FIG. 7 if the rotational speedof the transmission input shaft is greater than the low speed thresholdthat is greater than the emergency low speed threshold and thetemperature of the transmission fluid is greater than the temperaturethreshold. The fluid pressure required to be supplied by the variatortrim valve 70 to the spring pocket 230 of the dual pump pressureregulator valve 190 to position the spool 200 in the positionillustrated in FIG. 7 is as described hereinabove with respect to FIG.4.

Referring now to FIG. 8, another operating state of the dual pumppressure regulator valve 190 is shown. In the operating stateillustrated in FIG. 8, the variator pressure multiplex valve 220operates to fluidly couple a fixed reference pressure, rather than thevariable-pressure fluid outlet of the variator trim valve 70 as in thecase of FIGS. 4-7, to the fluid passageway 229 such that the fixedreference pressure is supplied to the spring pocket 230 of the dual pumppressure regulator valve 190 under at least one predefined operatingcondition. In the embodiment illustrated in FIG. 8, the variatorpressure multiplex valve 221 is fluidly coupled via a fluid passageway221 to exhaust (EX), and in this embodiment the variator pressuremultiplex valve 220 is operable under the at least one predefinedoperating condition to fluidly couple the fluid passageway 229 to thefluid passageway 221 to thereby exhaust the spring pocket 230 of thedual pump pressure regulator valve 190. In this case, the fluid pressurein the clutch main fluid passageway 65 is a constant-valued fluidpressure, e.g., 400 psi, and since the spring pocket 230 of the dualpump pressure regulator valve 190 is exhausted is a function of thebiasing force of the spring 218 and of the area of the face of the spool200 at the end 202 thereof. In alternative embodiments, the variatorpressure multiplex valve 221 may be fluidly coupled via one or morefluid passageways to one or more other constant-valued, positivereference pressures, and in such embodiments the variator pressuremultiplex valve 220 may be operable under the at least one predefinedoperating condition to fluidly couple the fluid passageway 229 to atleast one such fluid passageway to thereby supply a constant-valued,positive reference pressure to the spring pocket 230 of the dual pumppressure regulator valve 190. In such cases, the constant-valued,positive fluid pressure in the clutch main fluid passageway 65 is afunction of the value of the reference pressure supplied to the springpocket 230 of the valve 190, the biasing force of the spring 218 and ofthe area of the face of the spool 200 at the end 202 thereof.

In one illustrative embodiment, the at least one predefined operatingcondition under which the variator multiplex valve 220 fluidly couplesthe fixed reference pressure to the spring pocket 230 of the dual pumppressure regulator valve 190 includes one or more fault conditionsassociated with the transmission 14. Alternatively or additionally, theat least one predefined operating condition may include cold startconditions, e.g., cold operation of the transmission 14 prior to warmingup as a result of operation to at least a minimum operating temperature.Those skilled in the art will recognize one or more other operatingconditions under which the variator multiplex valve 220 may fluidlycoupled the fixed reference pressure to the spring pocket 230 of thedual pump pressure regulator valve 190, and any such one or more otheroperating conditions are contemplated by this disclosure. In any case,the variator pressure multiplex valve 220 is operable, under control ofthe control circuit 30, to selectively couple the fluid passageway 228to the fluid passageway 229 under “normal” operating conditions, or toselectively couple the fluid passageway 229 to the reference pressure,e.g., exhaust, under the at least one predefined operating condition,e.g., fault and/or cold start conditions. Further details relating tosuch control of the variator pressure multiplex valve 220 are describedin co-pending U.S. patent application Ser. No. ______, having attorneydocket number ATP-0054-USP/46582-212954.

When the dual pump pressure regulator valve 190 is controlled as justdescribed by supplying a constant-valued reference pressure to thespring pocket 230, the spool 200 is illustratively positioned asdescribed with respect to FIG. 6, i.e., with the fluid passageway 224fluid coupled to the fluid passageway 68 such that fluid in the clutchmain fluid passageway 65 is supplied to the clutch control section 58and to the variator switching sub-system 56C, and with the fluidpassageway 234 fluidly coupled to the fluid passageway 162 such thatfluid supplied by the pump 100 is supplied to the lubrication andcooling sub-system 160. The land 208 blocks the fluid passageway 232from the fluid passageway 224 such that fluid in the clutch main fluidpassageway 65 is not supplied to the lubrication and cooling sub-system160, and the check ball valve 101 is closed such that fluid supplied bythe pump 100 is supplied only to the lubrication and cooling sub-system160. In this embodiment, the biasing force of the spring 218 and thearea of the face of the end 202 of the spool 200 are selected such thatthe spool 200 is positioned as illustrated in FIG. 8 when theconstant-valued reference pressure, e.g., exhaust, is supplied to thespring pocket 230.

It will be understood that the concepts illustrated and described hereinwith reference to FIGS. 4-8 apply not only to automatic transmissionswhich include a variator, but to other types of motor vehicletransmissions. Referring now to FIG. 9, for example, one alternativetransmission embodiment is shown in which a fluid flow control section240 is implemented. In the illustrated embodiment, the motor vehicletransmission is a conventional motor vehicle transmission that includesa conventional integral or attached torque converter 250 rather than avariator. The fluid flow control section 240 is otherwise identical tothe fluid flow control section 98 illustrated and descried with respectto FIGS. 3-8, and like reference numbers are therefore used in FIG. 9 torepresent like components. In this embodiment, the dual pump pressureregulator valve 190 may be controlled as described hereinabove withrespect to FIGS. 4-8 to control fluid flow to the clutch control section58, the torque converter 250 and the lubrication and cooling sub-system160.

Referring now to FIG. 10, another example is shown of a further type ofmotor vehicle transmission in which the concepts illustrated anddescribed herein may apply. In the embodiment illustrated in FIG. 10,the motor vehicle transmission is a conventional motor vehicletransmission that includes only a clutch control section 58 and alubrication and cooling sub-system 160, and in which a fluid flowcontrol section 300 is implemented. In the illustrated embodiment, thefluid passageway 68 coupled to the dual pump pressure regulator valve190 is omitted. The fluid flow control section 300 is otherwiseidentical to the fluid flow control section 98 illustrated and descriedwith respect to FIGS. 3-8, and like reference numbers are therefore usedin FIG. 10 to represent like components. In this embodiment, the dualpump pressure regulator valve 190 may be controlled as describedhereinabove with respect to FIGS. 4 and 6-8 to control fluid flow to theclutch control section 58 and the lubrication and cooling sub-system 98.

While the invention has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

1. An apparatus for controlling fluid flow in a motor vehicletransmission, comprising: a first pump driven by an input shaft of thetransmission to supply fluid from a source of fluid to at least onefriction engagement device via a first fluid passageway, a second pumpdriven by the input shaft of the transmission to normally supply fluidfrom the source of fluid to a lubrication and cooling sub-system of thetransmission via a second fluid passageway, a first valve fluidlycoupled between the first and second fluid passageways and directingfluid from the second fluid passageway to the first fluid passagewaywhen fluid pressure in the second fluid passageway is greater than fluidpressure in the first fluid passageway by at least a threshold pressureamount, and a second valve fluidly coupled to the first and second fluidpassageways and to the lubrication and cooling sub-system, the secondvalve blocking the first and second fluid passageways from thelubrication and cooling sub-system when a flow rate of the fluid in thefirst fluid passageway is less than a first threshold fluid flow rate, atemperature of the fluid is greater than a temperature threshold and afluid flow demand is greater than a fluid flow demand threshold suchthat fluid pressure in the second fluid passageway exceeds the fluidpressure in the first fluid passageway by at least the thresholdpressure amount, whereby fluid is supplied by the first and second pumpsonly to the at least one friction engagement device via the first fluidpassageway.
 2. The apparatus of claim 1 wherein the first valvecomprises a ball check valve configured to allow fluid flow from thesecond fluid passageway to the first fluid passageway when the fluidpressure in the second fluid passageway is greater than the fluidpressure in the first fluid passageway by at least the thresholdpressure amount and to otherwise block fluid flow between the first andsecond fluid passageways.
 3. The apparatus of claim 1 wherein the secondvalve comprises a spool having one end in fluid communication with thefirst fluid passageway and an opposite end positioned in a spring pocketunder bias of a spring in the direction of the one end, the springpocket receiving fluid at a controlled pressure, and wherein a positionof the spool within the second valve is a function of the fluid pressurein the first passageway, the controlled pressure of the fluid in thespring pocket and a biasing force of the spring.
 4. The apparatus ofclaim 3 further comprising a trim valve having a fluid inlet fluidlycoupled to the first fluid passageway and a fluid outlet fluidly coupledto the spring pocket of the second valve, the trim valve responsive to acontrol signal to supply fluid at the controlled pressure to the springpocket of the second valve.
 5. The apparatus of claim 4 furthercomprising a control circuit including a memory having instructionsstored therein executable by the control circuit to produce the controlsignal.
 6. The apparatus of claim 5 further comprising means fordetermining a rotational speed of the input shaft of the transmission,wherein the memory has an emergency low speed threshold stored thereinthat is correlated with the first threshold fluid flow rate, and whereinthe instructions stored in the memory include instructions executable bythe control circuit to determine whether the flow rate of the fluid inthe first fluid passageway is less than a first threshold fluid flowrate by determining whether the rotational speed of the input shaft ofthe transmission is less than the emergency low speed threshold.
 7. Theapparatus of claim 6 further comprising means for determining atemperature of the fluid supplied by the first and second pumps andproducing a corresponding temperature value, wherein the temperaturethreshold and the fluid flow demand threshold are stored in the memory,and wherein the instructions stored in the memory include instructionsexecutable by the control circuit to determine the fluid flow demand andto produce the control signal if the rotational speed of the input shaftof the transmission is less than the emergency low speed threshold, thetemperature value is greater than the threshold temperature and thefluid flow demand is greater than the fluid flow demand threshold. 8.The apparatus of claim 5 wherein the instructions stored in the memoryinclude instructions executable by the control circuit to modulate thecontrol signal as a function of the fluid pressure in the firstpassageway and the biasing force of the spring such that the fluidpressure supplied by the trim valve to the spring pocket controls thespool to a position in which the second valve blocks the first andsecond fluid passageways from the lubrication and cooling sub-systemsuch that fluid is supplied by the first and second pumps only to the atleast one friction engagement device via the first fluid passageway. 9.The apparatus of claim 1 wherein the second valve blocks the first fluidpassageway from the lubrication and cooling sub-system and fluidlycouples the second fluid passageway to the lubrication and coolingsub-system when the flow rate of the fluid in the first fluid passagewayis greater than the first threshold fluid flow rate but less than asecond threshold fluid flow rate and the temperature of the fluid isless than the temperature threshold such that the fluid pressure in thesecond fluid passageway is less than the fluid pressure in the firstfluid passageway by at least the threshold pressure amount, wherebyfluid is supplied by the first pump only to the at least one frictionengagement device via the first fluid passageway and fluid is suppliedby the second pump only to the lubrication and cooling sub-system viathe second fluid passageway.
 10. The apparatus of claim 9 wherein thesecond valve couples the first and second fluid passageways to thelubrication and cooling sub-system when the flow rate of the fluid inthe first fluid passageway is greater than the second threshold fluidflow rate and the temperature of the fluid is greater than thetemperature threshold such that the fluid pressure in the second fluidpassageway is less than the fluid pressure in the first fluid passagewayby at least the threshold pressure amount, whereby fluid is supplied bythe first pump to the at least one friction engagement device and to thelubrication and cooling system via the first fluid passageway and fluidis supplied by the second pump to the lubrication and cooling sub-systemvia the second fluid passageway.
 11. The apparatus of claim 10 whereinthe second valve comprises a spool having one end in fluid communicationwith the first fluid passageway and an opposite end positioned in aspring pocket under bias of a spring in the direction of the one end,and wherein a position of the spool within the second valve is afunction of the fluid pressure in the first passageway, fluid pressurein the spring pocket and a biasing force of the spring, and wherein thesecond valve regulates fluid pressure within the first fluid passagewayto a fixed fluid pressure as a function of the biasing force of thespring and of an area of the one end of the spool when the spring pocketis exhausted.
 12. The apparatus of claim 11 further comprising means forselectively exhausting the spring pocket of the second valve.
 13. Theapparatus of claim 1 wherein the transmission further comprises anotherfluid-using sub-system in addition to the at least one frictionengagement device and the lubrication and cooling subsystem, the anotherfluid-using subsystem fluidly coupled to the second valve via a thirdfluid passageway, the second valve further blocking the first and secondfluid passageways from the third fluid passageway when the flow rate ofthe fluid in the first fluid passageway is less than the first thresholdfluid flow rate, the temperature of the fluid is greater than thetemperature threshold and the fluid flow demand is greater than thefluid flow demand threshold, whereby fluid flow to the anotherfluid-using sub-system via either of the first and second fluid pumps isblocked.
 14. The apparatus of claim 13 wherein the second valve blocksthe first fluid passageway from the lubrication and cooling sub-system,fluidly couples the first fluid passageway to the third fluid passagewayand blocks the second fluid passageway from the lubrication and coolingsub-system when the flow rate of the fluid in the first fluid passagewayis greater than the first threshold fluid flow rate but less than asecond threshold fluid flow rate, the temperature of the fluid isgreater than the temperature threshold and the fluid flow demand isgreater than the fluid flow demand threshold such that the fluidpressure in the second fluid passageway is less than the fluid pressurein the first fluid passageway by at least the threshold pressure amount,whereby fluid is supplied by the first and second pumps only to the atleast one friction engagement device and the another fluid-usingsub-system via the first fluid passageway.
 15. The apparatus of claim 14wherein the second valve blocks the first fluid passageway from thelubrication and cooling sub-system, fluidly couples the first fluidpassageway to the third fluid passageway and fluidly couples the secondfluid passageway to the lubrication and cooling sub-system when the flowrate of the fluid in the first fluid passageway is greater than thesecond threshold fluid flow rate but less than a third threshold fluidflow rate and the temperature of the fluid is less than the temperaturethreshold such that the fluid pressure in the second fluid passageway isless than the fluid pressure in the first fluid passageway by at leastthe threshold pressure amount, whereby fluid is supplied by the firstpump only to the at least one friction engagement device and the anotherfluid-using sub-system via the first fluid passageway and fluid issupplied by the second pump only to the lubrication and coolingsub-system via the second fluid passageway.
 16. The apparatus of claim15 wherein the second valve fluidly couples the first and second fluidpassageways to the lubrication and cooling sub-system and fluidlycouples the first fluid passageway to the third fluid passageway whenthe flow rate of the fluid in the first fluid passageway is greater thanthe third threshold fluid flow rate and the temperature of the fluid isgreater than the temperature threshold such that the fluid pressure inthe second fluid passageway is less than the fluid pressure in the firstfluid passageway by at least the threshold pressure amount, wherebyfluid is supplied by the first pump to the at least one frictionengagement device, the another fluid-using sub-system and thelubrication and cooling system via the first fluid passageway and fluidis supplied by the second pump to the lubrication and cooling sub-systemvia the second fluid passageway.
 17. The apparatus of claim 13 whereinthe second valve comprises a spool having one end in fluid communicationwith the first fluid passageway and an opposite end positioned in aspring pocket under bias of a spring in the direction of the one end,and wherein a position of the spool within the second valve is afunction of the fluid pressure in the first passageway, fluid pressurein the spring pocket and a biasing force of the spring, and wherein thesecond valve regulates fluid pressure within the first fluid passagewayto a fixed fluid pressure as a function of the biasing force of thespring and of an area of the one end of the spool when the spring pocketis exhausted.
 18. The apparatus of claim 17 further comprising means forselectively exhausting the spring pocket of the second valve.
 19. Theapparatus of any of claim 13 wherein the another fluid-using sub-systemcomprises one of a variator and a torque converter.
 20. An apparatus forcontrolling fluid flow in a motor vehicle transmission including atleast one friction engagement device and a fluid-using sub-systemseparate from and addition to the at least one friction engagementdevice, the apparatus comprising: a first pump driven by an input shaftof the transmission to supply fluid from a source of fluid to the atleast one friction engagement device via a first fluid passageway and tonormally supply fluid from the source of fluid to the fluid-usingsub-system via the first fluid passageway, a second pump driven by theinput shaft of the transmission to normally supply fluid from the sourceof fluid to a lubrication and cooling sub-system of the transmission viaa second fluid passageway, a first valve fluidly coupled between thefirst and second fluid passageways and directing fluid from the secondfluid passageway to the first fluid passageway when fluid pressure inthe second fluid passageway is greater than fluid pressure in the firstfluid passageway by at least a threshold pressure amount, and a secondvalve fluidly coupled to the first and second fluid passageways, to thefluid-using sub-system and to the lubrication and cooling sub-system,the second valve blocking the first and second fluid passageways fromthe lubrication and cooling sub-system and fluidly coupling the firstfluid passageway to the fluid-using sub-system when a flow rate of thefluid in the first fluid passageway is less than a first threshold fluidflow rate, a temperature of the fluid is greater than a temperaturethreshold and a fluid flow demand is greater than a fluid flow demandthreshold such that fluid pressure in the second fluid passagewayexceeds the fluid pressure in the first fluid passageway by at least thethreshold pressure amount, whereby fluid is supplied by the first andsecond pumps only to the at least one friction engagement device and tothe fluid-using sub-system via the first fluid passageway.